Image pickup apparatus having image pickup optical system

ABSTRACT

An image pickup apparatus comprising a first lens unit which comprises at least a negative lens element and at least a positive lens element and has negative refractive power, a second lens unit which has positive refractive power, and an optical path bending reflecting optical element which has a variable reflecting surface disposed in an airspace between a most object side lens component of the first lens unit and a most object side lens component of the second lens unit. This image pickup apparatus changes a magnification by moving the second lens unit along an optical axis and corrects a deviation of an image location by varying a shape of the variable reflecting surface of the reflecting optical element.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese application No.2001-080189, filed Mar. 21, 2001, the contents of which is incorporatedherein in its entirety by reference.

BACKGROUND OF THE INVENTION

a) Field of the Invention

The present invention relates to an improvement in an optical systemwhich is included in a photographic system, a view finder system,automatic exposure control system, an automatic focusing auxiliary lightillumination system or the like for an image pickup apparatus such as afilm camera, a digital camera, a video camera or the like.

b) Description of the Prior Art

Demands for thinner configurations of image pickup apparatuses such asfilm cameras, digital cameras, video cameras and the like become higherand higher year by year. It is therefore important to shorten totallengths of optical systems such as photographic optical systems and viewfinder optical systems to be used in the image pickup apparatuses.

Since there lies a limit in shortening a total length of such an opticalsystem by reducing a number of compositional lens elements, it isattempted to shorten a total length by bending an optical system using amirror.

For bending an optical system, however, it is necessary to reserve aspace for a bent portion, and a space for moving lens units in a zoomoptical system or moving lens unit(s) for focusing in particular is aptto be insufficient, thereby making it difficult to obtain a requiredzoom ratio and shorten an extremely short distance. In case of a viewfinder, it is difficult to shorten a total length since a space must bereserved for moving a lens unit to adjust or correct diopter.

Furthermore, it is desirable for automatic exposure control of an imagepickup apparatus to make variable a weighted coefficient distributionfor the so-called weighted mean light measurement according to a programof what portion of a photographing range of an object is to beconsidered at what ratio. There are adopted, for example, a centerweighted mean light measurement, spot light measurement and the like.For carrying out such a variable weighted mean light measurement, it iseffective to change a focus point location of a condenser lens componentwhich condenses rays on a sensor. In such a case, it is necessary to usea mechanism which changes a relative positional relation between thecondenser lens component and the sensor, thereby complicating an imagepickup apparatus.

On the other hand, zoom lens systems nowadays constitute a main currentof photographic optical systems for image pickup apparatuses and when anexclusive condenser optical system has a single focal point, a lightmeasuring area is changed relative to a photographing range of an objectby zooming, whereby the center weighted mean light measurement at a wideposition may be a mean light measurement at a tele position. In such acase, a condenser lens component which condenses rays on a sensor in alight measuring system must have a vari-focal function. When thecondenser lens has the vari-focal function, however, a magnificationchanging mechanism of the light measuring system is complicated and whenthe condenser lens component is interlocked with a zoom lens system of aphotographic system, the mechanism is more complicated.

Digital cameras (electronic cameras) have recently been attractingattention as cameras of a next generation which are to substitute forsilver salt 35 mm film cameras (Leica camera by popular name).

An effective image pickup surface of an image pickup device generallyused for a digital camera has a size which is much smaller than that ofa silver salt film. Therefore, the image pickup device has defect thatit has too large a depth of field can hardly provide an effect ofdefocus. In contrast, there is a case where pan-focus is desired.

In order to realize these effects, there is conceivable a method tocarry out an image processing so as to change an apparent depth of fieldby composing image data of an identical scene having focus points whichare different little by little. In such a case, however, it is necessaryto obtain a plurality of image data in a short time and at a high speedwhile changing a focus point.

It is therefore necessary to contrive optical systems at respectiveportions of an image pickup apparatus such as a camera, thereby not onlythinning a photographic system, a view finder system, a light measuringsystem, a range finding system at the respective portions but alsoenhancing performance of these systems.

In other words, it is necessary to configure the photographic system soas to exhibit predetermined performance of use even when an optical pathis bent, remove a moving space for diopter adjustment in the view findersystem, configure the light measuring system without complicating amechanism so as to be capable of changing a focal length of a condenselens having a simple composition so as to make variable a weightcoefficient distribution for the weighted mean light measurementaccording to a program of what portion of a photographic range of anobject is to be considered at what degree.

The light measuring system is configured so as to be capable of changinga focal length of a condenser lens system in order to change adistribution of weight coefficients in accordance with a magnificationchange of the photographic optical system.

Furthermore, it is necessary to configure the light measuring system soas to be capable of obtaining desired distributions of weightcoefficients from a wide position to a tele position in conjunction witha magnification change of a zoom lens system.

Furthermore, a light projector optical system of the range findingsystem is configured so as to have a simple composition withoutcomplicating a mechanism and be capable of changing a magnification ofthe light projector optical system in conjunction with a magnificationof the photographic optical system, and optimalizing a range findingregion from the wide position to the tele position.

Furthermore, it is necessary to obtain means for obtaining an image onwhich defocuses before and after a focus point are emphasized byreducing an apparent depth of field of an image photographed with animage pickup apparatus which uses an image pickup device having a smalleffective image pickup surface size.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an image pickupapparatus which comprises at least a view finder system, an automaticexposure control system, an automatic focusing mechanism and an opticalpath bending reflecting member which has an optical element having avariable shape included in optical systems comprised in these systems,and is configured to be capable of performing correction of an imagelocation, focusing and the like at a zooming stage by varying the shapeof a reflecting surface of the optical element having the variableshape.

Another object of the present invention is to provide an image pickupapparatus comprising an optical system which comprises a first lens unitdisposed at a stationary location, comprising a negative lens elementand a positive lens element and having negative refractive power and asecond lens unit having positive refractive power, an optical pathbending reflecting surface having a variable shape disposed between amost object side lens component and a second lens unit of the first lensunit, and is configured to change mainly a magnification by moving onlythe second lens unit and correct a deviation of an image location duringa magnification change by varying the shape of the reflecting surface.

Another object of the present invention is to provide an image pickupapparatus which comprises a first lens unit having positive refractivepower, a second lens unit having negative refractive power and anoptical path bending reflecting surface having a variable shape disposedon the image side of a most image side lens component of the second lensunit, and is configured to change a magnification by moving the secondlens unit along an optical axis and correct a deviation of an imagelocation by varying the shape of the reflecting surface during amagnification change.

Another object of the present invention is to provide an image pickupapparatus which comprises a first lens unit having positive or negativerefractive power, a second lens unit having negative refractive power, athird lens unit having positive refractive power and an optical pathbending reflecting surface having a variable shape disposed on theobject side of a most object side lens component of the second lensunit, and is configured to change a magnification by moving at least thethird lens unit and vary the shape of the reflecting surface by movingthe third lens unit for correcting a deviation of an image locationduring the magnification change.

Another object of the present invention is to provide an image pickupapparatus comprising a photographic optical system and a view finderwhich comprises, in order from the object side along an optical axis, anobjective lens system, an eyepiece system and image erecting reflectingmirrors, and is configured to form a real image between the objectivelens system and the view finder: one of the image erecting reflectingmirror having a variable shape.

Another object of the present invention is to provide an image pickupapparatus comprising a photographic optical system and a light measuringoptical system for range finding which has a function to determine anexposure time by measuring a light amount as a weighted mean of lightamounts at location within a photographing range of an object to bephotographed with the photographic optical system.

Another object of the present invention is to provide an image pickupapparatus comprising a photographic optical system, and a light source,a light projector optical system and a light measuring optical systemfor range finding: the light projector optical system being an opticalsystem consisting of a light projector optical system and an opticalpath bending reflecting optical element or an optical path bendingreflecting optical element and a light projector optical system whichare disposed in this order between the light source and an object to bephotographed by the photographic optical system, and the reflectingoptical element being a reflecting optical element having a variableshape.

Still another object of the present invention is to provide an imagepickup apparatus which comprises a photographic optical system, an imagepickup device, an optical path bending reflecting optical element havinga variable shape disposed between an object and the image pickup device,and a control system for controlling a variation of the shape of thereflecting optical element.

A further object of the present invention is to provide an image pickupapparatus comprising left and right photographic optical systems whichare disposed side by side, and a plurality of reflecting opticalelements which are disposed on the object side of the photographicoptical systems respectively for giving parallax between left and rightsides.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 4 are sectional views showing photographic optical systems tobe used in first to fourth embodiments of the image pickup apparatus ofthe present invention;

FIG. 5 is a diagram showing an example of a reflecting surface of avariable shape optical element;

FIGS. 6A and 6B are diagrams showing a fifth embodiment of the presentinvention;

FIG. 7 is a diagram showing a sixth embodiment of the present invention;

FIGS. 8A and 8B are diagrams showing a seventh embodiment of the presentinvention;

FIG. 9 is a diagram showing an eighth embodiment of the presentinvention;

FIGS. 10A, 10B, 10C and 10D are curves visualizing an outline ofaberrations in an image pickup apparatus according to the eighthembodiment;

FIGS. 11A and 11B are diagrams showing a ninth embodiment of the presentinvention;

FIGS. 12A, 12B and 12C are diagrams showing a tenth embodiment of thepresent invention;

FIG. 13 is a diagram showing a configuration of a view finder accordingto an eleventh embodiment of the present invention;

FIGS. 14 and 15 are diagrams showing twelfth and thirteenth embodimentsof the present invention;

FIGS. 16A, 16B and 16C are diagrams showing variations of a shape of areflecting optical element having a variable shape in an image pickupapparatus according to the thirteenth embodiment;

FIGS. 17A, 17B and 17C are diagrams showing light amount distributionsin conditions shown in FIGS. 16A, 16B and 16C respectively;

FIGS. 18A, 18B and 18C are diagrams showing variations of the shape ofthe reflecting optical element having the variable shape in zoomconditions of the image pickup apparatus according to the thirteenthembodiment;

FIGS. 19A, 19B and 19C are diagrams showing trimmed conditions of animage pickup surface of the image pickup apparatus according to thethirteenth embodiment;

FIGS. 20A, 20B and 20C are diagrams showing shapes of the reflectingsurface of the reflecting optical element having the variable shapecorresponding to the trimmed conditions shown in FIGS. 19A, 19B and 19C;

FIGS. 21A, 21B, 21C and 21D are diagrams showing a fourteenth embodimentof the present invention;

FIGS. 22A, 22B and 22C are diagrams showing a fifteenth embodiment ofthe present invention;

FIG. 23 is a diagram showing a light projecting condition by a lightprojector optical system in the fifteenth embodiment of the presentinvention;

FIG. 24A, 24B and 24C are diagrams showing a sixteenth embodiment of thepresent invention;

FIG. 25 is a diagram descriptive of an image processing by the imagepickup apparatus according to the sixteenth embodiment of the presentinvention;

FIGS. 26A and 26B are diagrams showing a seventeenth embodiment of thepresent invention;

FIG. 27 is a diagram showing a configurational example of reflectingoptical element having a variable shape to be used by the presentinvention;

FIG. 28 is a diagram showing an example of electrode to be used in FIG.27; and

FIG. 29 is a diagram showing another example of electrode to be used inFIG. 27.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An image pickup apparatus which has a first composition according to thepresent invention comprises an optical system (photographic lens system)which comprises a first lens unit disposed at a fixed location,comprising at least a negative lens element and at least a positive lenselement and having negative refractive power, a second lens unit havingpositive refractive power, and an optical path bending reflectingsurface having a variable shape which is disposed between a most objectside lens component of the first lens unit and a most object side lenscomponent of the second lens unit, performs mainly a magnificationchange by moving only the second lens unit, and corrects a deviation ofan image location by varying the shape of the reflecting surface duringthe magnification change.

The optical system of the image pickup apparatus according to thepresent invention is configured on the basis of a typical typephotographic optical system for digital cameras, or a zoom type lenssystem which comprises a first lens unit having negative refractivepower and a composite system on and after a second lens unit havingpositive refractive power, comprises, in order from the object side, afirst lens unit disposed at a fixed location, comprising at least anegative lens element and at least a positive lens element and havingnegative refractive power, a second lens unit having positive refractivepower and an optical path bending reflecting surface having a variableshape disposed between a most object side lens component of the firstlens unit and a most object side lens component of the second lens unit,performs mainly a magnification changing function by moving only thesecond lens unit along an optical axis and corrects a deviation of animage location during a magnification change by varying the shape of thereflecting surface.

An ordinary zoom lens system which consists of a first lens unit havingnegative refractive power and a rear lens group on and after a secondlens unit having positive refractive power as a whole moves the secondlens unit on the object side to change a magnification from a wideposition to a tele position and corrects a deviation of a focal pointlocation caused due to the magnification change by moving the first lensunit monotonously on the image side or while tracing a locus convex onthe image side.

The photographic optical system used in the image pickup apparatusaccording to the present invention is configured to use the first lensunit disposed at the fixed location, and adopts instead the optical pathbending reflecting surface having the variable shape and a controlsystem which is capable of freely varying the shape of the reflectingsurface, thereby correcting the deviation of the focal point location(deviation of an image surface) caused during a magnification change.Furthermore, the photographic optical system is configured to performalso focusing by varying the shape of the reflecting surface having thevariable shape.

This reflecting surface (the optical path bending reflecting opticalelement) consists, for example, of a thin film which has a reflectingsurface coated with a metal as described later, is connected to a powersource by way of a plurality of electrodes and variable resistors, andhas an arithmetical unit for controlling resistance values of thevariable resistors so that the shape of the reflecting surface is variedby controlling a distribution of electrostatic forces applied to thethin film.

An optical system which corrects a focal point location by varying ashape of a reflecting surface like the above described optical systemhas a correcting capability lower than that of an optical system whichcorrects a focal point location by mechanically moving a lens unit. Itis therefore desirable to configure an optical system so as to have apower distribution which shortens a moving distance required for a focalpoint location of a composite system of the first lens unit itself andthe reflecting optical element having the variable shape, that is, anobject location of the composite system on and after the second lensunit so that a correction amount is as small as possible.

For this reason, it is desirable that the composite system on and afterthe second lens unit has a magnification satisfying the followingcondition;0.5<ABS(βW)<ABS(βT)<1.8

-   -   wherein reference symbols ABS(βW) and ABS(βT) represent        magnifications of the composite system on and after the second        lens unit at the wide position and the tele position        respectively.

This condition utilizes a fact that a deviation of a focal pointlocation is generally small when magnifications of a composite system onand after a second lens unit are close to 1× at the wide position andthe tele position respectively. If an upper limit or a lower limit ofthis condition is exceeded, a focal point location will have a largecorrection amount and cannot be corrected sufficiently by varying ashape of a reflecting optical element having a variable shape.

An image pickup apparatus which has a second composition according tothe present invention adopts an optical system which comprises a firstlens unit having positive refractive power, a second lens unit havingnegative refractive power and an optical path bending reflecting surfacehaving a variable shape disposed on the image side of a most image sidelens component of the second lens unit, and is configured to perform amagnification change by moving the second lens unit along an opticalaxis and correct a deviation of an image location during themagnification change by varying the shape of the reflecting surface.

The optical system of the image pickup apparatus which has the secondcomposition is configured on the basis of a typical zoom type lenssystem for video cameras or one of types usable also for digital camerascomprising a first positive lens unit, a second negative lens unit and athird positive lens unit and characterized by comprising, in order fromthe object side, a first positive lens unit, a second negative lens unitand an optical path bending reflecting surface having a variable shapedisposed on the image side of a most image side lens component of thesecond lens unit, performing a magnification change by moving the secondlens unit along an optical axis and correcting a deviation of an focalpoint location caused during the magnification change by varying theshape of the above described reflecting surface. In this case, a numberof lens components and moving spaces on the object side of a location ofan optical path bent by the reflecting surface makes it impossible tosay that the composition exhibits a sufficient effect for a thinconfiguration, but the composition makes it possible to configure areflecting surface on and after the second lens unit as a reflectingsurface having a variable shape, correct a deviation of a focal pointlocation caused during a magnification change by varying the shape ofthe above described reflecting surface and perform controls such asfocusing with the reflecting surface.

Furthermore, an image pickup apparatus which has a third compositionaccording to the present invention uses an optical system which isconfigured to comprise, in order from the object side, a first lens unithaving positive or negative refractive power, a second lens unit havingnegative refractive power, a third lens unit having positive refractivepower and an optical path bending reflecting surface having a variableshape disposed on the object side of a most object side lens componentof the second lens unit, and is configured to perform a magnificationchange by moving at least the third lens unit along an optical axis andvary the shape of the reflecting surface having the variable shape tocorrect a deviation of an image surface location caused during themagnification change.

The optical system used in the third composition is configured on thebasis of the typical type lens system for video cameras or another zoomtype lens system usable for digital cameras consisting of a firstpositive or negative lens unit, a second negative lens unit, a thirdpositive lens unit and a fourth positive lens unit, comprises in orderfrom the object side the first positive or negative lens unit disposedat a fixed location, the second negative lens unit, the third positivelens unit and the optical path bending reflecting surface having thevariable shape disposed on the object side of the most object side lenscomponent of the second lens unit, performs the magnification change bymoving at least the third lens unit along the optical axis and correctsthe deviation of the focal point location caused during themagnification change by varying the shape of the reflecting surfacehaving the variable shape.

A zoom lens system which comprises a first lens unit having positive ornegative refractive power, a second lens unit having negative refractivepower and a third lens unit having positive refractive power ordinarilymoves the third lens unit on the image side to change a magnificationfrom a wide position to a tele position and corrects a deviation of afocal point location caused during the magnification change by movingall or some of lens units disposed on the image side of the third lensunit in a direction monotonously or while tracing a locus convex on theobject side or the image side.

For thinning an image pickup apparatus by bending an optical path, it ispreferable to dispose an optical path bending reflecting surface at anylocation between a most object side lens component of a first lens unitand a most object side lens component of a second lens unit. In such acase, a space for disposing the optical path bending electing surfacemakes a moving space for the second lens unit insufficient. A vari-focalratio is lowered accordingly, but a control system is disposed to permitfreely varying a shape of the optical path bending reflecting surfacefor making up for the lowered vari-focal ratio and a variation of afocal length of a composite system of the first lens unit itself, areflecting optical element having a variable shape and the second lensunit itself is corrected by varying the shape of the reflecting surface.

Furthermore, it is also possible to bend an optical path by disposing areflecting optical element having a variable shape at any location inand after the second lens unit and correct a deviation of a focal pointlocation caused during a magnification change by varying the shape ofthe reflecting optical element. In this case also, focusing may beperformed by varying the shape of the reflecting optical element havingthe variable shape. In this case, it is adequate to vary the shape ofthe reflecting optical element in a direction perpendicular to a firstbending direction.

In addition, the second lens unit may be fixed so far as a large valuecan be given to a variation of a focal length of the composite system ofthe first lens unit, the optical element having a variable shape and thesecond lens unit by imparting a vari-focal function to lens unit(s)disposed after the second lens unit and disposing a reflecting opticalelement having a variable shape at any location between the most objectside lens component of the first lens unit and the most object side lenscomponent of the second lens unit.

For the optical system used in the image pickup apparatus according tothe present invention described above, it is desirable that the controlsystem for controlling the variation of the shape of the reflectingsurface has additional functions described as the following items 1 to7:

1. The control system has not only a function for changing a paraxialamount but also a function for correcting aberrations by varying theshape of the reflecting surface. For example, the control systemdetermines a paraxial amount by components of low orders of a curvedsurface and corrects aberrations by components of high orders like anature of an ordinary aspherical lens element whose paraxial amount isdetermined by a term of the second order of a formula expressing anaspherical surface and whose aberrations are corrected by terms of thefourth and higher orders.

2. The control system for controlling the shape of the reflectingsurface has a function for control additionally with lens control datafor preventing vibration. That is, it is possible to prevent vibrationby varying a shape or an angle of a mirror surface instead of detectinga vibration amount of a lens system and mechanically correcting an imagelocation so as to be immovable on an image surface. In order words, itis possible to perform vibration prevention with quick response byapplying quick response of a mirror having a variable shape to avibration prevention function.

3. The control system has a function for controlling the optical systemso as to follow positional shift of a main object (for example, acelestial body) with time lapse during long exposure so that an image isnearly immovable on an image surface.

4. The control system has a function for controlling the optical systemso as to be focused on a best fit curved surface (on which a sum ofsquares of depths at points is minimum, for example) from multi-pointrange finding data. A typical example is swing photographing which iseffective for bringing the optical system into focus on an object whichis not located on a single plane.

5. The control system has a function for controlling the optical systemso as to be capable of changing aberration conditions for differentmodes such as a resolution emphasized mode, a distortion mode, a softfocus mode and the like. This function allows a user to selectaberration conditions at his will at a certain degree.

6. The control system has a function for storing data corresponding toshape variation amounts of a mirror which is to be used for changing afocal length in accordance with changes of specifications for CCDs andthe like to be used and controlling the optical system while consideringthe above described data in controlling a shape of a mirror having avariable shape. Though a digital camera must be matched withspecifications for a CCD, this function allows specifications to bevariable at a certain degree and to be modifiable including a size of aCCD.

7. The control system has a function for storing a paraxial amount of aphotographic lens system and result data of curvature of field intomemory means and controlling a shape of a mirror having a variable shapewhile considering the above described result data. This function more orless moderates narrowing of an allowable variation range of a result aspicture elements are used in a larger number.

An image pickup apparatus which has a fourth composition according tothe present invention comprises a view finder in addition to aphotographic optical system; the view finder being a view finder of atype comprising, in order from the object side along an optical path, anobjective lens system and an eyepiece system for forming a real imagebetween the objective lens system and the eyepiece system, that is, aKeplerian view finder, and configured to correct diopter by freelyvarying a shape of one of image erecting reflecting surfaces. Thoughdiopter can ordinarily be changed by moving all or some of lenscomponents of an eyepiece system, an image pickup apparatus is thickenedby moving spaces required of the lens components.

The view finder used in the image pickup apparatus according to thepresent invention therefore uses an eyepiece system which is fixed andone of image erecting reflecting surfaces which is configured as areflecting optical element having a variable shape, and is configured tochange diopter by varying the shape of the reflecting optical element.This image pickup apparatus permits selecting diopter at a user's willand is capable of automatically correcting diopter using a range findingresult on a photographic system or zoom condition data.

When a photographic lens system has a high zoom ratio and a certaindegree of magnification is reserved for a view finder at a wideposition, the view finder inevitably has a high magnification at a teleposition, whereby diopter is changed in too large an amount from aninfinite distance to an extremely short distance when peeped through theview finder at the tele position. Furthermore, diopter is apt to bedeviated largely at the wide position and the tele position.

It is sufficient for solving this problem to match diopter with a mainobject using a range finding result on a photographic lens system orautomatically correct diopter for each focal length using zoom conditiondata. Though description has been made above of correction of diopter,it is possible to similarly correct parallax which is differentdependently on focal lengths and object distances.

An image pickup apparatus which has a fifth composition according to thepresent invention comprises a light measuring system for performingrange finding and the like which has a function for picking up an imageof an object as well as a function for determining an exposure time bymeasuring a light amount as a weighted mean of light amounts atlocations within a photographing range of an object at an image pickupstage and measures the light amount for the latter function. This lightmeasuring system consists, in order from a side of the object, acondenser lens system, an optical path bending reflecting opticalelement and a photosensor or an optical path bending reflecting opticalelement, a condenser lens system and a photosensor. It is appropriate toconfigure an optical path bending reflecting optical element as areflecting optical element having a variable shape, dispose a controlsystem capable of freely varying the shape of the reflecting opticalelement in such a light measuring optical system so that a distributionof weight coefficients in a photographing range of an object is variableand use the light measuring optical system in an image pickup apparatus.

The image pickup apparatus can be configured so as to be capable ofperforming two or more of a spot light measurement, a multi-spot lightmeasurement, center weighted light measurement and a pattern lightmeasurement.

Furthermore, it is preferable that an image pickup apparatus which has aphotographic optical system consisting of a zoom lens system isconfigured to comprise a control system which is capable of changing alight measuring range in conjunction with a change of a photographingrange. Furthermore, an image pickup apparatus may be configured to havea function for trimming and outputting an image pickup range, that is,the so called electronic zoom function. In this case, it is preferableto configure the image pickup apparatus so as to comprise a controlsystem which changes a light measuring range in conjunction with achange of a trimming range.

An optical path bending reflecting optical element consists of a thinfilm which has a reflecting surface coated with a metal and is connectedto a power source by way of a plurality of electrodes and variableresistors, has an arithmetic unit for controlling resistance values ofthe variable resistors and varies a shape of the reflecting surface bycontrolling a distribution of electrostatic forces applied to the thisfilm.

An image pickup apparatus which has a sixth composition according to thepresent invention comprises a light projector optical system for rangefinding, which is disposed separately from a photographic opticalsystem, has a function to pick up an image of an object and a rangefinding function at an image pickup time, or is an optical system whichconsists of the light projector optical system and an optical pathbending reflecting optical element or an optical path bending reflectingoptical element and a light projector optical system arranged in thisorder between a light source and the object: the optical path bendingreflecting optical element being a reflecting optical element having avariable shape and having a control system for controlling a shapevariation. This control system is capable of changing a light projectionrange or a light projection location on the object. In a case where animage pickup optical system of an image pickup apparatus is a zoom lenssystem in particular, it is possible to optimalize a light measuringregion from a wide position to a tele position by configuring the imagepickup apparatus so as to comprise a control system which is capable ofchanging a light projection range or a light projection location on anobject in conjunction with a change of a photographing range of the zoomlens system. When an image pickup system has the function for trimmingand outputting a photographing range (the so-called electronic zoomfunction), it is proper to configure the image pickup apparatus so as tocomprise a control system which is capable of changing a lightprojection range or a light projection location on an object.

An image pickup apparatus which has a seventh composition according tothe present invention comprises an imaging optical system forphotographing and an image pickup device for photographing, a reflectingoptical element which bends an optical axis of the imaging opticalsystem ranging from an object through the imaging optical system to theimage pickup device and is configured as an optical element having avariable shape and a control system for freely varying the shape of thereflecting optical element, is capable of releasing a shutter andpicking up images a plurality of times within a short time, and has acontrol system which is capable of freely varying the shape of thereflecting optical element at a high speed in conjunction with a shiftof a focal point location from the image pickup device at each shutterrelease and makes it possible to photograph at a high speed a pluralityof images of a nearly identical scene which have different focusedpoints.

It is preferable to configure this image pickup apparatus so as to havea function which finally forms an image by composing the plurality ofimages of the nearly identical scene which have the different focusedpoints and a function permitting freely changing a vignetted leveldependently on a depth degree of the object so that the image pickupapparatus is capable of outputting data of the composed image. Moreover,the image pickup apparatus is applicable to animations and monitoring aswell as inspections with a magnifying optical system having a shallowdepth when the image pickup apparatus is configured to be capable ofperforming real time processing for the functions.

An image pickup apparatus which has an eighth composition according tothe present invention is configured to be capable of obtaining astereoscopic image. In other words, the image pickup apparatus which hasthe eighth composition comprises two left and right photographic opticalsystems which are arranged side by side and a plurality of reflectingoptical elements which are disposed on the object side of the left andright photographic optical systems respectively for producing parallaxbetween left and right sides, and is configured to image images of anidentical object formed by the left and right photographic opticalsystems on a left half and a right half on the image side of thephotographic optical systems with slightly different parallax betweenthe left and right sides. Some of the reflecting optical elementsdisposed on the object side of the left and right photographic opticalsystems are configured to have reflecting surfaces variable in shapes orthe like. Accordingly, the image pickup apparatus is capable ofobtaining a desired stereoscopic image by controlling the reflectingsurfaces of the reflecting optical elements variable in the shapes orthe like so as to vary the shapes, positions or angles of the reflectingoptical elements, thereby controlling a vergence angle or a focus point.

The reflecting surface variable in shape (reflecting surface of thereflecting optical element having the variable shape) used in the imagepickup apparatus according to the present invention consists, forexample, of a thin film or the like having a reflecting surface coatedwith a metal as described later with reference to drawings, which isconnected to a power source by way of a plurality of electrodes andvariable resistors, and has an arithmetic unit for controlling values ofthe variable resistors so that the shape of the reflecting surface isvaried by controlling a distribution of electrostatic forces applied tothe thin film.

FIG. 1 shows a composition of a first embodiment of the image pickupapparatus which has the first composition according to the presentinvention in a condition where the image pickup apparatus is focused onan object located at an infinite distance.

As shown in FIG. 1, an optical system used in the image pickup apparatusaccording to the first embodiment comprises, in order from the objectside, a first lens unit G1 which consists of a negative lens elementLN1, a mirror VM having a variable shape, a negative lens element LN2and a positive lens element LP3 and has negative refractive power as awhole, a stop S, a second lens unit G2 which consists of a positive lenselement LP4 and a cemented lens component consisting of a positive lenselement LP5 and a negative lens element LN6, is moved along an opticalaxis for a magnification change and has positive refractive power as awhole, a third lens unit G3 which consists of a positive lens elementLP7, filters F which consists of an infrared cut filter and a low passfilter, and a CCD. In addition, a reference symbol IS represents animage pickup surface of the CCD.

In other words, the optical system according to the first embodiment isan optical system which comprises the first lens unit G1 comprising twonegative lens elements and a positive lens element, the second lens unitG2 having positive refractive power, the optical path bending reflectingoptical element VM having the variable shape disposed between an objectside lens element LN1 which is an object side lens component of thefirst lens unit and a lens element LP4 which is an object side lenscomponent of the second lens unit G2, changes a magnification by movingonly the second lens unit G2 and is to be used in the image pickupapparatus which has the first composition according to the presentinvention.

This optical system is configured to move the second lens unit G2 alongthe optical axis for changing the magnification and vary the shape ofthe variable shape mirror VM to change power of this mirror, therebycorrecting a deviation of a location of an image surface caused due tothe magnification change.

Furthermore, the optical system is focused on an object located at ashort distance simply by varying the shape of the variable shape mirrorVM.

FIG. 2 shows a photographic optical system used in a second embodimentof the image pickup apparatus according to the present invention. Thephotographic optical system according to the second embodiment comprisesa first lens unit G1 consisting of a positive lens element LP1, a secondlens unit G2 consisting of a negative lens element LN2 and a cementedlens component which consists of a negative lens element LN3 and apositive lens element LP4 and has negative refractive power, a mirror VMwhich is used for bending an optical path and has a variable shape, athird lens unit G3 consisting of a positive lens element LP5, a cementedlens component which consists of a positive lens element LP6 and anegative lens element LN7 and has negative refractive power and apositive lens element LP8, filters F, and a CCD (only an image pickupsurface IS is shown).

A photographic optical system according to the second embodimentcomprises the first lens unit G1 having positive refractive power, thesecond lens unit G2 having negative refractive power and the opticalpath bending reflecting optical element having a variable shape disposedon the image side of a negative lens element which is a most image sidelens component of the second lens unit G2, changes a magnification bymoving the second lens unit G2 and is to be used in the second ecomposition according to the present invention.

The second embodiment is configured to change a magnification from awide position W to a tele position T by moving the second lens unit G2which is disposed on the object side of the optical path bending mirrorVM along the optical axis as indicated by an arrow, and correct adeviation of an image location caused during the magnification change byvarying a shape of the variable shape mirror VM. Furthermore, the secondembodiment is focused on an object located at a short distance simply byvarying the shape of the variable shape mirror.

FIG. 3 shows a third embodiment of the image pickup apparatus accordingto the present invention. As shown in this drawing, a photographicoptical system used in this image pickup apparatus comprises a firstlens unit G1 which consists of a positive lens element LP1 and anegative lens element LN2, a variable shape mirror VM, a second lensunit G2 which consists of a cemented lens component consisting of anegative lens element LN3 and a positive lens element LP4, a stop S, athird lens unit G3 which consists of a positive lens element LP5, and acemented lens component consisting of a positive lens element LP6 and anegative lens element LN7, a fourth lens unit G4 which consists of apositive lens element LP8, a filter F and a CCD (image pickup surfaceIS).

The photographic optical system according to the third embodimentcomprises the first lens unit G1 having positive refractive power, thesecond lens unit G2 having negative refractive power and the third lensunit G3 having positive refractive power, changes a magnification bymoving at least the third lens unit G3, uses the optical path bendingreflecting optical element VM having the variable shape which isdisposed on the object side of a most object side lens element LN3 ofthe second lens unit G2 and is to be used in the image pickup apparatuswhich has the third composition according to the present invention.

The optical system according to the third embodiment changes amagnification from a wide position to a tele position by moving thethird lens unit G3 and the fourth lens unit G4 along an optical axis asindicated by an arrow in the drawing. During the magnification change,the optical system corrects a deviation of an image location by varyinga shape of the mirror VM having the variable shape and moving the secondlens unit G2 along the optical axis as indicated by an arrow (traced ina dashed line).

In addition, the second lens unit may be moved or fixed during themagnification change.

FIG. 4 is a sectional view illustrating a fourth embodiment of the imagepickup apparatus according to the present invention.

The fourth embodiment has a composition similar to that of the thirdembodiment or is an image pickup apparatus comprising an optical systemwhich has the third composition according to the present invention, butis different from the third embodiment in that the fourth embodimentuses a mirror VM having a variable shape which is disposed on a mostobject side in the optical system.

In other words, a photographic optical system according to the fourthembodiment comprises, in order from the object side, a mirror VM havinga variable shape, a first lens unit G1 which consists of a positive lenselement LP1, a second lens unit G2 which consists of a negative lenselement LN2 and a cemented lens component consisting of a negative lenselement LN3 and a positive lens element LP4, a stop S, a third lens unitG3 which consists of a positive lens element LP5 and a cemented lenscomponent consisting of a positive lens element LP6 and a negative lenselement LN7, and a fourth lens unit G4 which consists of a positive lenselement LP8, changes a magnification location by moving the fourth lensunit or varying the shape of the mirror VM having the variable shape.

It is possible for each of the image pickup apparatuses according to thefirst through fourth embodiments shown in FIGS. 1 through 4 not only tochange a paraxial amount such as surface power but also to correctaberrations by varying the shape of the mirror having the variableshape. Furthermore, it is preferable to configure the mirror so as tohave an aspherical surface within an effective surface of the reflectingsurface. In a case where the reflecting surface has power in particular,eccentric aberrations will be produced if the reflecting surface hasrotationally symmetric shape and a light bundle is incidenteccentrically on this reflecting surface. It is therefore preferable toconfigure the reflecting surface of the mirror having the variable shapeso as to have a curved surface which is not rotationally symmetric.

Furthermore, off axial rays produce distortion which is not rotationallysymmetric when a light bundle is incident eccentrically as describedabove. In order to correct eccentric aberrations produced due toeccentricity, the reflecting surface of the mirror having the variableshape is configured as a curved surface which is symmetric with regardto only a plane including optical axes of rays incident and reflectedonto and by the reflecting surface.

FIG. 5 is a diagram showing a form of the mirror VM having the variableshape, which is symmetric with regard to a plane S(1, 2) which includesan optical axis 1 of a light bundle incident on the mirror VM having thevariable shape and an optical axis 2 of the light bundle reflected bythe mirror VM.

When the optical system is focused on an object located at an infinitedistance, the mirror having the variable shape has a planar surface, butwhen the optical system is to be focused on an object located at a shortdistance, the shape of the mirror is varied so as to be an asphericalsurface which is symmetric with regard to the plane S(1, 2) as shown inFIG. 5, thereby focusing the optical system on the object located at theshort distance and correcting the eccentric aberrations.

The mirror having the variable shape therefore makes it possible notonly to configure an image pickup apparatus compact as a whole but alsoallow the image pickup apparatus to correct aberrations and havefavorable optical performance.

FIGS. 6A and 6B are diagrams showing means for preventing influences dueto vibrations such as hand vibrations.

FIG. 6A shows an image pickup apparatus free from band vibrations,whereas FIG. 6B shows an image pickup apparatus in a condition where ahand vibration correcting function is effective.

When an image pickup apparatus is turned downward and an optical axisdirection 1′ of a photographic optical system LS is turned downward asshown in FIG. 6B, for example, from the condition free from thevibrations shown in FIG. 6A, a shape of the reflecting optical elementVM having the variable shape is varied so that reflected rays travel ina direction of an optical axis 2 and an optical axis of rays incident ona CCD or image pickup means 3 such as a film is not inclined. In thiscase, it is preferable not only to vary the shape of the reflectingelement VM having the variable shape for obtaining a function to preventthe optical axis from being inclined but also to correct the shape ofthe reflecting element VM having the variable shape as a whole so assuppress variations of aberrations.

FIG. 7 shows an example of image pickup apparatus which is configured toform an image always at an identical location on an image surface duringexposure for a long time of a moving object such as a celestial body.

The image pickup apparatus is configured to vary a shape (curvature) ofa variable shape mirror continuously as a moving object ST such as acelestial body moves from ST1 to ST2, thereby forming an object such asa star always at an identical location on an image surface duringexposure for a long time.

FIGS. 8A and 8B are diagrams showing an embodiment which performs rangefinding to points at different object distances and is focused on a bestfit curved surface (where a sum of squares of distances to the points isminimum, for example).

Shown in FIGS. 8A and 8B is an example in which a shape of a mirrorhaving a variable shape is varied so as to focus an photographic opticalsystem nearly on an object located at a distance C intermediate betweena view at a long distance A and an object located at a short distance B.

In FIG. 8A, power to be applied to light bundles is varied on the basisof an image formed by the view finder system dependently on the objectsat the distances A, B and C selected by a viewing ray input device (notshown), and power applying portions of the mirror having the variableshape are configured to be varied with signals from a CPU.

FIG. 9 shows a ninth embodiment of the image pickup apparatus accordingto the present invention. This embodiment is an image pickup apparatuswhich comprises an optical system using a mirror having a variable shapeand is configured to allow selection among various modes such as anormal photographic mode, a resolution emphasis mode, a distortioncorrecting mode and a soft focus mode.

An image pickup apparatus 10 has a dial 11 for selection among the abovedescribed modes and a shape of a mirror VM having a variable shape isvaried into a shape in a mode directed by the dial 11 by way of a CPU 12as shown in FIG. 9.

FIGS. 10A, 10B, 10C and 10D show aberration conditions obtained byvarying a shape of a reflecting surface of the reflecting opticalelement VM having the variable shape in respective modes in the imagepickup apparatus shown in the above described FIG. 9. Out of thesedrawings, FIG. 10A is the normal mode, FIG. 10B is the resolutionemphasis mode, FIG. 10C is the distortion correcting mode and FIG. 10Dis the soft focus mode. As shown conceptionally in these drawings,spherical aberration, astigmatism and distortion are corrected with goodbalance in the normal mode shown in FIG. 10A, spherical aberration iscorrected favorably in particular in the resolution emphasis mode shownin FIG. 10B, distortion is corrected favorably in particular in thedistortion correcting mode shown in FIG. 10C and spherical aberration isproduced remarkably in the soft focus mode shown in FIG. 10D.

The image pickup apparatus having a composition shown in FIG. 9 isconfigured to vary the shape of the reflecting optical element VM havingthe variable shape so as to obtain the above described aberrationconditions in an optical system and permit photographing desired images.

FIGS. 11A and 11B shows a tenth embodiment of the image pickup apparatusaccording to the present invention.

This embodiment is an example of image pickup apparatus which isconfigured so as to be capable of corresponding to image pickup devicesCCD(A) and CCD(B) which have different numbers of picture elements. Inother words, CCD(A) has a diagonal length of an image pickup surfacewhich is longer than that of CCD(B). The tenth embodiment permitsselection between the image pickup devices CCD(A) and CCD(B) to bedisposed on an image pickup surface of an image pickup optical system asdescribed above. However, a photographic field angle is changeddependently on the diagonal lengths of the image pickup surfaces whenthe image pickup devices are simply replaced with each other.

The image pickup apparatus according to the tenth embodiment reduces adifference between the field angles by varying a surface shape of areflecting optical element having a variable shape as indicated by asolid line and a dashed line as shown in FIG. 11B when the image pickupdevice is replaced with the other. Specifically, the difference betweenvariations of the field angles is reduced by varying the surface shapeof the reflecting optical element having the variable shape so as to bea planar surface as shown as a variable shape reflecting optical elementVM1 when CCD(A) is to be used or a convex surface as shown as a variableshape reflecting optical element VM2 when CCD(B) is to be used.

FIGS. 12A, 12B and 12C are diagrams showing an eleventh embodiment ofthe image pickup apparatus according to the present invention.

The eleventh embodiment is an example of image pickup apparatus which isconfigured to focus a photographic optical system by varying a shape ofa reflecting optical element VM having a variable shape on the basis ofa signal obtained by a measurement with an automatic focusing mechanism.

An image pickup apparatus according to the eleventh embodiment is shownin FIG. 12A, in which a reference symbol LS represents an image pickupoptical system, a reference symbol VM designates a variable shapemirror, a reference numeral 15 denotes an automatic focusing mechanism,a reference numeral 16 represents a CPU and a reference numeral 17designates a memory. An optimum shape of the mirror having the variableshape is calculated by sending a signal obtained by a light measurementwith the automatic focusing mechanism to the CPU 16 as shown in FIG.12A, an object distance is calculated with this signal and calling outdata stored in the memory. A signal which controls the mirror VM havingthe variable shape so as to have the calculated shape is transmittedfrom the CPU 16, thereby varying a surface shape of the mirror VM havingthe variable shape and focusing the image pickup optical system.

FIGS. 12B and 12C show shapes of the reflecting optical element VMhaving the variable shape (FIG. 12B) and curvature of field(astigmatism) which correspond to distances to objects (FIG. 12C) whichare calculated on the basis of light measurements with the image pickupapparatus shown in FIG. 12A. In these drawings, a shape of a reflectingsurface and aberration conditions in a condition focused on an objectlocated at 50 cm are shown at an upper stage, a shape of the reflectingsurface and aberration conditions in a condition focused on an objectlocated at 1 m are shown at a middle stage, and a shape of thereflecting surface and aberration conditions in a condition focused onan object located at an infinite distance are shown at a lower stage.

FIG. 13 shows an embodiment comprising a Keplerian view finder which hasthe fourth composition according to the present invention or an examplewhere one of image erecting reflecting surfaces is configured as avariable shape mirror.

In FIG. 13, a reference numeral 21 represents an objective lens systemwhich consists of a negative lens element and positive lens elements, areference numeral 22 designates a visual field frame which is disposedat a location of an intermediate image surface, a reference numeral 23denotes a roof prism, a reference numeral 24 represents a pentagonalprism which has a convex surface of incidence 24 a and a role of acondenser lens, and a reference numeral 25 designates an eyepieceoptical system consisting of an eyepiece.

In this embodiment, a surface 24 b which is a second reflecting surfaceof the pentagonal prism 24 is configured as a mirror having a variableshape which is varied to adjust diopter for zooming, photographing anobject located at a short distance, and correcting a vergence anglebetween the prism 24 and a photographic lens system which is not shownin FIG. 13. Furthermore, it is possible to vary the shape of the surfacefor correcting a vergence angle so as to match with a near-sighted eye,a far sighted eye and an astigmatic eye of observers.

Furthermore, a view finder shown in the drawing is configured to changea visual field for observation by moving a plurality of lens elementsout of lens units (elements) composing the objective lens system 21.

FIG. 14 shows an embodiment of an image pickup apparatus comprising aview finder having another composition in which a mirror having avariable shape is used as a reflecting surface in a view finder which issimilar to the view finder having the above described composition.

In FIG. 14, a reference numeral 21 represents an objective lens system,reference symbols VM1 and VM2 designate mirrors having variable shapesrespectively, a reference numeral 26 denotes a roof mirror and areference numeral 25 represents an eyepiece optical system; thesecomponents composing a view finder, for example, such as that shown inFIG. 13. Furthermore, the two mirrors VM1 and VM2 having the variableshapes are disposed in the view finder. Furthermore, a reference numeral15 represents an automatic focusing mechanism, a reference numeral 16designates a CPU, a reference symbol LS denotes a photographic lenssystem, for example, such as that shown in FIG. 1, 2, 3 or 4, areference numeral 27 represents a release button, a reference numeral 28designates a zoom switch, a reference numeral 29 denotes a drivingsystem for moving lens units for changing a magnification of thephotographic lens system (zoom lens system) LS and a reference numeral30 represents an image pickup device.

This image pickup apparatus performs a calculation with the CPU 16according to an instruction from the zoom switch 28, for example, andmoves the lens units of the photographic lens system along an opticalaxis with the driving system 29 so as to set a magnification at aninstructed level. Simultaneously, shapes of the mirrors having thevariable shapes are varied with a signal from the CPU 16 to correct adeviation of an image surface caused due to a magnification change whichis effected by moving the lens units with the driving system 29.

Furthermore, the objective lens system 21 of the view finder consists,in order from the object side, of a negative lens unit, a positive lensunit and a positive lens unit, for example, as shown in FIG. 12A, and isconfigured to obtain a visual field for observation corresponding to aphotographing field angle by moving a plurality of lens units out of thethree lens units. Furthermore, the mirror VM2 on a side of the eyepiecesystem 25 out of the variable shape mirrors VM1 and VM2 may be utilizedfor adjusting diopter so as to match it with diopter of an observer'seye.

Furthermore, the release button 27 inputs a signal from the automaticfocusing mechanism into the CPU 16, the CPU 16 calculates aphotographing object distance on the basis of this signal and calculateddata is sent to a mirror VM3 having a variable shape of the photographiclens system LS to vary a shape of a reflecting surface, therebyperforming focusing.

On the other hand, a view finder system is configured to vary a shape ofthe mirror VM1 having the variable shape on a side of the objective lenssystem 21 in order to correct parallax between the view finder systemand a photographing range on the basis of the photographing objectdistance and a signal representing a zoom condition of the photographiclens system. Simultaneously, the view finder system varies a shape ofthe mirror VM2 having the variable shape on a side of the eyepiecesystem so as to match diopter between a focused object point and avisual field frame.

Out of the shapes of the three mirrors VM1, VM2 and VM3 having thevariable shapes, those which are traced in solid lines are surfaceshapes in a condition where the photographic lens system is focused onan object located at an infinite distance, whereas those which aretraced in dashed lines designate surface shapes in a condition where thephotographic lens system is focused on an object located at a shortdistance.

The image pickup apparatus according to this embodiment is capable ofcorrecting parallax and diopter for the photographing range easily asdescribed above.

FIGS. 15, 16A, 16B, 16C, 17A, 17B, 17C, 18A, 18B, 18C, 19A, 19B and 19Cshow an embodiment of an image pickup apparatus which is configured todetermine an exposure time at a stage to photograph an object bymeasuring light amounts at locations within a photographing range of theobject and calculating a weighted mean.

In FIG. 15, a reference symbol LS represents a photographic opticalsystem, for example, such as that shown in any one of FIGS. 1 to 4 whichis a zoom lens system for forming an image on a light receiving surfaceof image recording means such as an image pickup device, CCD or a film,and a signal indicating a zoom condition of the photographic opticalsystem is input into a CPU 16. Furthermore, a reference numeral 31designates a light measuring system which consists, in order from theobject aside, of a positive lens component L, a mirror VM having avariable shape and a light measuring element 32. Though the shown lightmeasuring element 32 has a single small light receiving surface, a lightmeasuring element may have a single light receiving surface or aplurality of light receiving surfaces which are patterned.

In an image pickup apparatus according to the embodiment shown in FIG.15, rays which are incident on the positive lens component 1, andreflected by the mirror VM having the variable shape are measured by thelight measuring element 32 and measured data is input into the CPU 16.Furthermore, a reference numeral 33 represents a light measuring modeselecting mechanism which inputs a signal indicating a selected modeinto the CPU 16 upon selection of a specific mode. Furthermore, areference numeral 34 designates a trimming control mechanism which has afunction to permit modifying a photographing range when the imagerecording means 30 is an image pickup device or a visual field stop fordetermining an image pickup range is disposed right before an imagesurface when the image recording means 30 is a film surface.

In the image pickup apparatus according to this embodiment, the shape ofthe mirror VM having the variable shape of the light measuring system 31which is disposed on a front surface of the apparatus is varied into asurface shape calculated by the CPU 16 based on a zoom condition of thephotographic optical system LS and a light measuring mode selected bythe light measuring mode selecting mechanism.

The above described light measuring mode is selectable, for example, outof a center weighted light measurement, a center spot light measurementmode and a center weighted mean light measurement mode.

FIGS. 16A, 16B, 16C, 17A, 17B and 17C variations of a surface shape(FIGS. 16A, 16B and 16C) and distribution of light amounts.(FIGS. 17A,17B and 17C) in the light measuring modes selected in the image pickupapparatus shown in FIG. 15.

FIG. 16A shows a shape of the mirror VM having the variable shape whenthe center spot light measurement mode is selected by the lightmeasuring mode selecting mechanism 33 and a distribution of lightamounts in this mode is shown in FIG. 17A.

Furthermore, FIG. 16B shows a shape of the mirror VM having the variableshape when the center spot measurement is selected and a distribution oflight amounts in this mode is shown in FIG. 17B.

Furthermore, FIG. 16C shows a shape of the mirror having the variableshape when the center weighted mean light measurement mode is selectedand a distribution of light amounts in this mode is shown in FIG. 17C.

Furthermore, FIGS. 18A, 18B and 18C show operations for modifying lightmeasuring ranges dependently on zoom conditions of an image pickupsystem (the photographic lens system): FIG. 18A showing a shape of areflecting surface at a wide position of the image pickup system, FIG.18B showing a shape of the reflecting surface at an intermediate focallength of the image pickup system and FIG. 18C showing a shape of thereflecting surface at a tele position of the image pickup system.

In the center weighted light measurement mode, the shape of thereflecting surface is convex in a zoom condition on a wide position sideof the intermediate focal length or concave in a zoom condition on atele position side of the intermediate focal length as shown in FIGS.18A, 18B and 18C. Accordingly, the image pickup apparatus is capable ofmodifying the light measuring range as a photographing range changes.

FIGS. 19A, 19B, 19C, 20A, 20B and 20C show operations for modifying thelight measuring range dependently on image pickup surfaces and trimmingconditions in the image pickup apparatus having the composition shown inFIG. 15. FIG. 19A shows a trimming condition in a high vision mode inwhich the photographing range is maximum, FIG. 19B shows a trimmingcondition in a panoramic mode in which a vertical size is shortened andFIG. 19C shows a trimming condition in a classic mode in which ahorizontal size is shortened. FIGS. 20A, 20B and 20C show shapes of themirror VM having the variable shape which are different dependently onthe modes shown in FIGS. 19A, 19B and 19C.

The mirror VM having the variable shape has a planar shape (basic shape)in the high vision mode as shown in FIG. 20A, a cylindrical shape convexin a vertical direction in the panoramic mode for shortening a verticalsize of the light measuring range as shown in FIG. 20B or a cylindricalshape convex in a horizontal direction in the classic mode forshortening a horizontal size of the light measuring range. The imagepickup apparatus is capable of modifying the light measuring rangedependently on photographing conditions as described above.

FIGS. 21A, 21B, 21C and 21D show an embodiment in which a lightreceiving surface of a light measuring sensor SF has an area of acertain degree relative to an image pickup range. FIG. 21A shows acomposition of this embodiment in which mirrors VM1 and VM2 havingvariable shapes are disposed on both sides of a lens component L asshown in the drawing. FIG. 21B is a diagram showing a ray condensingcondition in the embodiment shown in FIG. 21A when it is configured tochange a degree of gradation on the light measuring sensor by changing asurface shape of the mirror VM2 having the variable shape on a side ofthe sensor. FIG. 21C shows a variation of a light measuring pattern inthe ray condensing condition shown in FIG. 21B and the embodiment iscapable of measuring light in various modes as shown in FIG. 21C.

Though a photographing range is changed by zooming a photographic lenssystem, the embodiment varies the shapes of the mirrors VM1 and VM2having the variable shapes of the light measuring system shown in FIG.21A, thereby being capable of changing an image magnification on thelight measuring sensor as shown in FIG. 21D without changing a lightmeasuring pattern and maintaining a light measurement mode desired by aphotographer.

FIGS. 22A, 22B and 22C show an embodiment of an image pickup apparatuswhich comprises a photographing system for picking up an image of anobject and a range finding system for measuring a distance at an imagepickup stage.

In FIG. 22A, a reference symbol LS represents a zoom lens system whichis a photographic lens system, reference numerals 41 a, 41 b and 41 cdesignate light emitting elements, a reference numeral 42 denotes alight projector lens component, a reference numeral 40 represents arange finding system consisting of a mirror having a variable shape orthe like, and a reference numeral 34 designates a trimming mechanism.

In this image pickup apparatus, information such as a magnification issent from the photographic lens system LS to a CPU 16, information ofthe trimming mechanism 34 is input into the CPU 16 and a shape of themirror VM having the variable shape is varied based on the informationin the CPU 16. Accordingly, rays from the light emitting elements 41 a,41 b and 41 c are projected through the light projector lens component42 to an object after the rays are reflected by the mirror VM having thevariable shape.

FIG. 22B shows a trimming condition and FIG. 22C shows a variation of ashape of the mirror VM having the variable shape in the trimmingcondition.

As shown in these drawings, the mirror VM having the variable shape hasa planar surface shape for a usual screen size, whereas the mirror VMhaving the variable shape has a convex cylindrical surface havingcurvature in a vertical direction when a screen is trimmed as shown on aright side in FIG. 22B.

FIG. 23 shows an example where a light projecting range of the threelight sources 41 a, 41 b and 41 c is changed as the photographic lenssystem LS is zoomed in the image pickup apparatus shown in FIG. 22A. InFIG. 23, a light projecting direction (direction toward an object) isidentical to that in FIG. 22A, and the light sources 41 a, 41 b and 41 care shown on a right side. Furthermore, the mirror VM having thevariable shape is omitted in FIG. 23.

Rays from the three light sources are varied as shown in FIG. 23 byvarying the shape of the mirror VM having the variable shape, therebymaking it possible to change a photographing range at a wide positionfrom a photographing range at a tele position.

FIGS. 24A, 24B and 24C show an embodiment of an image pickup apparatuswhich is capable of picking up at a high speed a plurality of imageswhich have different focused locations.

FIG. 24A and FIG. 24B show a configuration of the above described imagepickup apparatus, which consists of a photographic lens system LS, amirror VM having a variable shape, an image sensor 45, a memory 46, animage processing device 47 and the like.

This image pickup apparatus is configured to keep stationary arefractive optical element of the photographic lens system LS and varythe shape of the mirror VM having the variable shape in the lens systemat a high speed in response to shutter release so as to focus the lenssystem on a plurality of points. Furthermore, the image sensor 45 whichis a CCD or the like records images of the points in focused conditionsand inputs the images into the memory 46. Based on the images stored inthe memory 46, the image pickup apparatus is capable of performing aprocessing to compose an image having an optional apparent depth withthe image processing device 47.

Furthermore, the fixed lens system LS shown in FIG. 24B may be replacedwith a movable lens system as shown in FIG. 24C when the image pickupapparatus is to pickup only an image.

FIG. 25 shows an image processing by the image pickup apparatus whichhas the configuration shown in FIG. 24A. FIG. 25 shows an example toprocess three images: 50 a at a short distance, 50 b at an intermediatedistance and 50 c at a far distance. On these images 50 a, 50 b and 50c, solid lines represent sharply focused portions, chain lines designateslightly defocused portions and dashed lines denote vignetted portions.

Signals of these images 50 a, 50 b and 50 c are input into the imageprocessing device 47 for image processing.

By this image processing, the image pickup apparatus is capable ofoutputting an image 51 a having a pan-focus effect, an image 51 b havinga vignetted effect and an image 51 c in soft focus.

By extracting and composing only portions having high contrast from theimages 50 a, 50 b and 50 c, the image pickup apparatus is capable ofproviding a clear image like the image 51 a shown as a conceptionalimage which is in good focus from a near scene to a far scene. In otherwords, the image pickup apparatus is capable of providing an image whichhas the pan focus effect.

In other to obtain an image having the above described effect byordinary photographing, it is necessary to expose a film for a long timein a stop down condition, but an image may be blurred when an objectmoves.

In contrast, the image pickup apparatus according to this embodimentdoes not require stopping down and is therefore capable of providing animage in pan focus through the image processing even the image pickupapparatus is held by hand during photographing.

Furthermore, it is possible to obtain an image having such a vignettedeffect as to emboss a main object by adopting a main object in focus andmost vignetted images before and after the main objects from the abovedescribed images 51 a, 51 b and 51 c. This vignetted effect isconvenient for emphasizing a main object as in photographing a person orthe like.

For a digital camera or a video camera which uses an image sensor, therelies a limit in shallowing a depth of field for configuring an imagesensor an optical system compact. An image processing such as that bythe image pickup apparatus shown in FIGS. 24A, 24B and 24C makes itpossible to compose an image having a depth of field shallower than onebeyond performance of a camera.

Furthermore, the image pickup apparatus is capable of providing an imagelike the image 51 c which has a soft focus effect giving a softimpression like the image 51 c by adopting portions in focus andvignetted portions at the same time to compose an image.

FIGS. 26A and 26B show an embodiment of an image pickup apparatus whichis configured for obtaining a stereoscopically observable image byforming images of an identical object on a left half and a right half ofan image pickup surface with slight parallax, and uses mirrors havingvariable shapes as some of a plurality of reflecting optical elementsdisposed on the object side of a photographic optical system for givingparallax between the left and right side images: FIG. 26A being aconfigurational diagram and FIG. 26B being a perspective view.

In FIGS. 26A and 26B, a reference numeral 60 represents a main lenssystem, a reference numeral 61 designates image pickup means such as animage pickup device like a CCD in a film surface, reference numerals 62a, 63 a, 62 b and 63 b denote left and right reflecting opticalelements, out of which 62 a and 63 a are the mirrors having the variableshapes.

This image pickup apparatus forms a stereoscopically observable image byreflecting left and right light bundles which are incident with slightparallax using the reflecting optical elements 62 a, 63 a, 62 b and 63 brespectively, and imaging the light bundles onto the left half and righthalf respectively of the image pickup means 61 using the main lenssystem 60.

This image pickup apparatus can be focused from an object located at aninfinite distance onto an object located at a short distance by varyingshapes of the left and right mirrors 62 a and 63 a having the variableshapes from shapes traced in solid lines to shapes traced in dashedlines.

An examples of a mirror having a variable shape (reflecting opticalelement having a variable shape) to be used in the image pickupapparatus according to the present invention will be described below.

FIG. 27 shows a mirror 70 having a variable shape consisting of apiezoelectric element 70 disposed between a thin film 70 a andelectrodes 70 b which are disposed on a supporting base 71. Voltageswhich are to be applied to the piezoelectric element 70 c are changeddependently on the electrodes 70 b so as to cause different localelongations and contractions of the piezoelectric element 70 c, therebyvarying a shape of the thin film 70 a. The electrode 70 b may have ashape concentrically divided as shown in FIG. 28, rectangularly dividedas shown in FIG. 29 or another adequately selectable shape. In thedrawings, a reference numeral 72 blur sensor which is connected to anarithmetic unit 73 for detecting, for example, blur of a digital cameraand changing voltages to be applied to the electrodes 70 b by way of thearithmetic unit 73 and variable resistors 74 so that the shape of thethin film 70 a is varied so as to compensate for image disturbance dueto the blur. At this stage, focusing, temperature compensation and thelike are also performed while simultaneously taking into considerationsignals from a temperature sensor 75, a humidity sensor 76 and adistance sensor 77. In this case, it is preferable to configure the thinfilm 70 a so as to have a thickness at a certain degree since a stressproduced due to the variation of the shape of the piezoelectric element70 c is also applied to the thin film 70 a.

1. An image pickup apparatus comprising: an image pickup optical systemwhich comprises, in order from the object side, a first lens unitdisposed at a fixed location, comprising at least a negative lenselement and at least a positive lens element and has negative refractivepower, a second lens unit disposed next to said first lens unit andhaving positive refractive power, and an optical path bending reflectingoptical element having a variable shape disposed between a most objectside lens component of said first lens unit and a most object side lenscomponent of said second lens unit, and is configured to change amagnification by moving only said second lens unit along an opticalaxis.
 2. The image pickup apparatus according to claim 1, wherein aparaxial amount of said image pickup optical system is changed andaberrations are corrected by varying a surface shape of said reflectingoptical element having the variable shape.
 3. The image pickup apparatusaccording to claim 1, wherein a surface shape of said reflecting opticalelement having the variable shape is varied on the basis of lens controldata for reducing an influence due to vibrations.
 4. The image pickupapparatus according to claim 1, configured to control the shape of saidreflecting optical element having the variable shape so that an image ofa main object is nearly immovable on an image surface during exposurefor a long time.
 5. The image pickup apparatus according to claim 1,further comprising a multi-point range finding mechanism, wherein theshape of said reflecting optical element having the variable shape isvaried so that the image pickup optical system is brought into focus oneach point using data provided from said multi-point range findingmechanism.
 6. The image pickup apparatus according to claim 1, wherein asurface shape of said reflecting optical element having the variableshape is varied so as to obtain optional aberration conditions in saidimage pickup optical system.
 7. The image pickup apparatus according toclaim 1, comprising an image pickup device, wherein a surface shape ofsaid reflecting optical element having the variable shape is varied soas to change a focal length of said image pickup lens system incorrespondence to a change of said image pickup device.
 8. The imagepickup apparatus according to claim 1, configured to control a surfaceshape of said reflecting optical element having the variable shapetaking into consideration data of a paraxial amount or curvature offield in said image pickup optical system.
 9. The image pickup apparatusaccording to claim 8, comprising: a view finder which automaticallyadjusts diopter by varying the surface shape of said reflecting opticalelement having the variable shape on the basis of data of a focusedcondition or a zoom condition of said image pickup optical system. 10.The image pickup apparatus according to claim 8, configured to vary thesurface shape of said optical system having the variable shape on thebasis of data of a focused condition or a zoom condition of said imagepickup optical system.
 11. The image pickup apparatus according to claim8, configured to be capable of performing two or more of a spot lightmeasurement, a multi-spot light measurement, a center weighted lightmeasurement and center weighted mean light measurement and a patternlight measurement.
 12. An image pickup apparatus comprising: an imagepickup optical system comprises, in order from the object side, a firstlens unit having positive refractive power, a second lens unit havingnegative refractive power and an optical path bending reflecting surfacehaving a variable shape which is disposed on the image side of a mostimage side optical component of said second lens unit, and is configuredto change a magnification by moving said second lens unit along anoptical axis, wherein said second lens unit is moved only in a directionfrom said object side toward an image side to change the magnificationfrom a wide position to a tele position, and wherein a third lens unitis disposed successively to said second lens unit, and said third lensunit is kept stationary at a time of a change in magnification.
 13. Animage pickup apparatus comprising: an image pickup optical system whichcomprises, in order from the object side, a first lens unit havingpositive refractive power, a second lens unit having negative refractivepower and an optical path bending reflecting surface having a variableshape disposed on the image side of a most image side lens component ofsaid second lens unit, and is configured to change a magnification bymoving said second lens unit along an optical axis, wherein a paraxialamount of said image pickup optical system is changed and aberrationsare corrected by varying the optical path bending reflecting surfacehaving the variable shape.
 14. An image pickup apparatus comprising: animage pickup optical system which comprises, in order from the objectside, a first lens unit having positive refractive power, a second lensunit having negative refractive power and an optical path bendingreflecting surface having a variable shape disposed on the image side ofa most image side lens component of said second lens unit, and isconfigured to change a magnification by moving said second lens unitalong an optical axis, wherein the optical path bending reflectingsurface having the variable shape is varied on the basis of lens controldata for reducing an influence due to vibrations.
 15. An image pickupapparatus comprising: an image pickup optical system which comprises, inorder from the object side, a first lens unit having positive refractivepower, a second lens unit having negative refractive power and anoptical path bending reflecting surface having a variable shape disposedon the image side of a most image side lens component of said secondlens unit, and is configured to change a magnification by moving saidsecond lens unit along an optical axis, wherein said image pickupapparatus is configured to control the optical path bending reflectingsurface having the variable shape so that an image of a main object isnearly immovable on an image surface during exposure for a long time.16. An image pickup apparatus comprising: an image pickup optical systemwhich comprises, in order from the object side, a first lens unit havingpositive refractive power, a second lens unit having negative refractivepower and an optical path bending reflecting surface having a variableshape disposed on the image side of a most image side lens component ofsaid second lens unit, and is configured to change a magnification bymoving said second lens unit along an optical axis, wherein said imagepickup apparatus further comprises a multi-point range findingmechanism, the optical path bending reflecting surface having thevariable shape is varied so that the image pickup optical system isbrought into focus on each point using data provided from saidmulti-point range finding mechanism.
 17. An image pickup apparatuscomprising: an image pickup optical system which comprises, in orderfrom the object side, a first lens unit having positive refractivepower, a second lens unit having negative refractive power and anoptical path bending reflecting surface having a variable shape disposedon the image side of a most image side lens component of said secondlens unit, and is configured to change a magnification by moving saidsecond lens unit along an optical axis, wherein the optical path bendingreflecting surface having the variable shape is varied so as to obtainoptional aberration conditions in said image pickup optical system. 18.An image pickup apparatus comprising: an image pickup optical systemwhich comprises, in order from the object side, a first lens unit havingpositive refractive power, a second lens unit having negative refractivepower and an optical path bending reflecting surface having a variableshape disposed on the image side of a most image side lens component ofsaid second lens unit, and is configured to change a magnification bymoving said second lens unit along an optical axis, wherein said imagepickup apparatus comprises an image pickup device, the optical pathbending reflecting surface having the variable shape is varied so as tochange a focal length of said image pickup lens system in correspondenceto a change of said image pickup device.
 19. An image pickup apparatuscomprising: an image pickup optical system which comprises, in orderfrom the object side, a first lens unit having positive refractivepower, a second lens unit having negative refractive power and anoptical path bending reflecting surface having a variable shape disposedon the image side of a most image side lens component of said secondlens unit, and is configured to change a magnification by moving saidsecond lens unit along an optical axis, wherein said image pickupapparatus is configured to control the optical path bending reflectingsurface having the variable shape taking into consideration data of aparaxial amount or curvature of field in said image pickup opticalsystem.
 20. The image pickup apparatus according to claim 19,comprising: a view finder which automatically adjusts diopter by varyingan optical path bending reflecting surface having the variable shape onthe basis of data of a focused condition or a zoom condition of saidimage pickup optical system.
 21. The image pickup apparatus according toclaim 19, configured to vary the optical path bending reflecting surfacehaving the variable shape on the basis of data of a focused condition ora zoom condition of said image pickup optical system.
 22. The imagepickup apparatus according to claim 19, configured to be capable ofperforming two or more of a spot light measurement, a multi-spot lightmeasurement, a center weighted light measurement and center weightedmean light measurement and a pattern light measurement.